[Intel-gfx] [PATCH 1/4] drm: Add helper for DP++ adaptors
Zanoni, Paulo R
paulo.r.zanoni at intel.com
Thu Mar 31 19:25:36 UTC 2016
Em Ter, 2016-02-23 às 18:46 +0200, ville.syrjala at linux.intel.com
escreveu:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Add a helper which aids in he identification of DP dual mode (aka.
> DP++)
> adaptors. There are several types of adaptors specified:
> type 1 DVI, type 1 HDMI, type 2 DVI, type 2 HDMI
>
> Type 1 adaptors have a max TMDS clock limit of 165MHz, type 2
> adaptors
> may go as high as 300MHz and they provide a register informing the
> source device what the actual limit is. Supposedly also type 1
> adaptors
> may optionally implement this register. This TMDS clock limit is the
> main reason why we need to identify these adaptors.
>
> Type 1 adaptors provide access to their internal registers and the
> sink
> DDC bus through I2C. Type 2 adaptors provide this access both via I2C
> and I2C-over-AUX. A type 2 source device may choose to implement
> either
> or both of these methods. If a source device implements only the
> I2C-over-AUX method, then the driver will obviously need specific
> support for such adaptors since the port is driven like an HDMI port,
> but DDC communication happes over the AUX channel.
>
> This helper should be enough to identify the adaptor type (some
> type 1 DVI adaptors may be a slight exception) and the maximum TMDS
> clock limit. Another feature that may be available is control over
> the TMDS output buffers on the adaptor, possibly allowing for some
> power saving when the TMDS link is down.
>
> Other user controllable features that may be available in the
> adaptors
> are downstream i2c bus speed control when using i2c-over-aux, and
> some control over the CEC pin. I chose not to provide any helper
> functions for those since I have no use for them in i915 at this
> time.
> The rest of the registers in the adaptor are mostly just information,
> eg. IEEE OUI, hardware and firmware revision, etc.
Please run a spell checker and do some proof-reading both in the commit
message and in the code comments. Multiple instances of "sizo",
"Hoever", "adator", "Identyfy", etc. I also spotted some typos in the
next commits.
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
> drivers/gpu/drm/Makefile | 2 +-
> drivers/gpu/drm/drm_dp_dual_mode_helper.c | 328
> ++++++++++++++++++++++++++++++
> include/drm/drm_dp_dual_mode_helper.h | 80 ++++++++
> 3 files changed, 409 insertions(+), 1 deletion(-)
> create mode 100644 drivers/gpu/drm/drm_dp_dual_mode_helper.c
> create mode 100644 include/drm/drm_dp_dual_mode_helper.h
>
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 6eb94fc561dc..22228ef50f36 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -23,7 +23,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
>
> drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o
> drm_probe_helper.o \
> drm_plane_helper.o drm_dp_mst_topology.o
> drm_atomic_helper.o \
> - drm_kms_helper_common.o
> + drm_kms_helper_common.o drm_dp_dual_mode_helper.o
>
> drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
> drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> new file mode 100644
> index 000000000000..bfe511c09568
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> @@ -0,0 +1,328 @@
> +/*
> + * Copyright © 2016 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person
> obtaining a
> + * copy of this software and associated documentation files (the
> "Software"),
> + * to deal in the Software without restriction, including without
> limitation
> + * the rights to use, copy, modify, merge, publish, distribute,
> sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom
> the
> + * Software is furnished to do so, subject to the following
> conditions:
> + *
> + * The above copyright notice and this permission notice shall be
> included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
> EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
> EVENT SHALL
> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM,
> DAMAGES OR
> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
> OTHERWISE,
> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
> USE OR
> + * OTHER DEALINGS IN THE SOFTWARE.
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/export.h>
> +#include <linux/i2c.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <drm/drm_dp_dual_mode_helper.h>
> +#include <drm/drmP.h>
> +
> +/**
> + * DOC: DP dual mode (aka. DP++) adaptor helpers
> + *
> + * Helper functions to deal with DP dual mode adaptors.
> + *
> + * Type 1:
> + * Adaptor registers (if any) and the sink DDC bus may be accessed
> via I2C.
> + *
> + * Type 2:
> + * Adaptor registers and sink DDC bus can be accessed either via I2C
> or
> + * I2C-over-AUX. Source devices may choose to implement either one
> or
> + * both of these access methods.
> + */
> +
> +#define DP_DUAL_MODE_SLAVE_ADDRESS 0x40
> +
> +/**
> + * drm_dp_dual_mode_read - Read from the DP dual mode adaptor
> register(s)
> + * adapter: I2C adapter for the DDC bus
> + * offset: register offset
> + * buffer: buffer for return data
> + * size: sizo of the buffer
> + *
> + * Reads @size bytes from the DP dual mode adaptor registers
> + * starting at @offset.
> + *
> + * Returns:
> + * 0 on success, negative error code on failure
> + */
> +ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
> + u8 offset, void *buffer, size_t size)
> +{
> + struct i2c_msg msgs[] = {
> + {
> + .addr = DP_DUAL_MODE_SLAVE_ADDRESS,
> + .flags = 0,
> + .len = 1,
> + .buf = &offset,
> + },
> + {
> + .addr = DP_DUAL_MODE_SLAVE_ADDRESS,
> + .flags = I2C_M_RD,
> + .len = size,
> + .buf = buffer,
> + },
> + };
> + int ret;
> +
> + ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
> + if (ret < 0)
> + return ret;
> + if (ret != ARRAY_SIZE(msgs))
> + return -EPROTO;
No retries needed here or below? (asking this due to the comment in
drm_edid.c about retries)
> +
> + return 0;
> +}
> +
> +/**
> + * drm_dp_dual_mode_write - Write to the DP dual mode adaptor
> register(s)
> + * adapter: I2C adapter for the DDC bus
> + * offset: register offset
> + * buffer: buffer for write data
> + * size: sizo of the buffer
> + *
> + * Writes @size bytes to the DP dual mode adaptor registers
> + * starting at @offset.
> + *
> + * Returns:
> + * 0 on success, negative error code on failure
> + */
> +ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
> + u8 offset, const void *buffer, size_t
> size)
> +{
> + struct i2c_msg msg = {
> + .addr = DP_DUAL_MODE_SLAVE_ADDRESS,
> + .flags = 0,
> + .len = 1 + size,
> + .buf = NULL,
> + };
> + void *data;
> + int ret;
> +
> + data = kmalloc(msg.len, GFP_TEMPORARY);
> + if (!data)
> + return -ENOMEM;
> +
> + msg.buf = data;
> +
> + memcpy(data, &offset, 1);
> + memcpy(data + 1, buffer, size);
> +
> + ret = i2c_transfer(adapter, &msg, 1);
> +
> + kfree(data);
> +
> + if (ret < 0)
> + return ret;
> + if (ret != 1)
> + return -EPROTO;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_dp_dual_mode_write);
> +
> +static bool is_hdmi_adaptor(const char
> hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN])
> +{
> + static const char
> dp_dual_mode_hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] =
> + "DP-HDMI ADAPTOR\x04";
> +
> + return memcmp(hdmi_id, dp_dual_mode_hdmi_id,
> + sizeof(dp_dual_mode_hdmi_id)) == 0;
> +}
> +
> +/**
> + * drm_dp_dual_mode_detect - Identyfy the DP dual mode adaptor
> + * adapter: I2C adapter for the DDC bus
> + *
> + * Attempt to identify the type of the DP dual mode adaptor used.
> + *
> + * Note that when the answer is @DRM_DP_DUAL_MODE_NONE it's not
So how about adding a new or just renaming it to
DRM_DP_DUAL_MODE_UNKNOWN? Let's not assume everybody is going to read
the docs.
> + * certain whether we're dealing with a native HDMI port or
> + * a type 1 DVI dual mode adaptor. The driver will have to use
> + * some other hardware/driver specific mechanism to make that
> + * distinction.
> + *
> + * Returns:
> + * The type of the DP dual mode adaptor used
> + */
> +enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct
> i2c_adapter *adapter)
> +{
> + char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] = {};
> + uint8_t adaptor_id = 0x00;
> + ssize_t ret;
> +
> + /*
> + * Let's see if the adaptor is there the by reading the
> + * HDMI ID registers.
> + *
> + * Note that type 1 DVI adaptors are not required to
> implemnt
> + * any registers, and that presents a problem for detection.
> + * If the i2c transfer is nacked, we may or may not be
> dealing
> + * with a type 1 DVI adaptor. Some other mechanism of
> detecting
> + * the presence of the adaptor is required. One way would be
> + * to check the state of the CONFIG1 pin, Another method
> would
> + * simply require the driver to know whether the port is a
> DP++
> + * port or a native HDMI port. Both of these methods are
> entirely
> + * hardware/driver specific so we can't deal with them here.
> + */
> + ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_HDMI_ID,
> + hdmi_id, sizeof(hdmi_id));
> + if (ret)
> + return DRM_DP_DUAL_MODE_NONE;
> +
> + /*
> + * Sigh. Some (maybe all?) type 1 adaptors are broken and
> ack
> + * the offset but ignore it, and instead they just always
> return
> + * data from the start of the HDMI ID buffer. So for a
> broken
> + * type 1 HDMI adaptor a single byte read will always give
> us
> + * 0x44, and for a type 1 DVI adaptor it should give 0x00
> + * (assuming it implements any registers).
So shouldn't we just try to read from 0x00 to 0x1F in a single shot?
Would this work for your specific adaptor? It would be interesting to
know.
> Fortunately neither
> + * of those values will match the type 2 signature of the
> + * DP_DUAL_MODE_ADAPTOR_ID register so we can proceed with
> + * the type 2 adaptor detection safely even in the presence
> + * of broken type 1 adaptors.
> + */
> + ret = drm_dp_dual_mode_read(adapter,
> DP_DUAL_MODE_ADAPTOR_ID,
> + &adaptor_id,
> sizeof(adaptor_id));
> + if (ret || (adaptor_id != (DP_DUAL_MODE_TYPE_TYPE2 |
> + DP_DUAL_MODE_REV_TYPE2))) {
> + if (is_hdmi_adaptor(hdmi_id))
> + return DRM_DP_DUAL_MODE_TYPE1_HDMI;
> + else
> + return DRM_DP_DUAL_MODE_TYPE1_DVI;
> + } else {
> + if (is_hdmi_adaptor(hdmi_id))
> + return DRM_DP_DUAL_MODE_TYPE2_HDMI;
> + else
> + return DRM_DP_DUAL_MODE_TYPE2_DVI;
> + }
> +}
> +EXPORT_SYMBOL(drm_dp_dual_mode_detect);
> +
> +/**
> + * drm_dp_dual_mode_max_tmds_clock - Max TMDS clock for DP dual mode
> adaptor
> + * adapter: I2C adapter for the DDC bus
> + *
> + * Determine the max TMDS clock the adaptor supports based on the
> + * DP_DUAL_MODE_MAX_TMDS_CLOCK register. The register is mandatory
> for
> + * type 2 adaptors, optional for type 1 adaptors. Hoever, as some
> type 1
> + * adaptors are broken (see comments in drm_dp_dual_mode_detect()
> for the
> + * details) one probably shouldn't use this with type 1 adaptors at
> all.
> + * Type 1 adaptors should anyway be always limited to 165 MHz.
I always assume programmers are as bad as possible, so I wonder if we
should just also call drm_dp_dual_mode_detect() here. Also try the
trick of reading the whole thing at once instead of the specific
address. Same goes for the other functions. I also see that this would
make patches 2-4 different, so this is just an idea, not a requirement.
> + *
> + * Returns:
> + * Maximum supported TMDS clock rate for the DP dual mode adaptor in
> kHz.
> + */
> +int drm_dp_dual_mode_max_tmds_clock(struct i2c_adapter *adapter)
> +{
> + uint8_t max_tmds_clock;
> + ssize_t ret;
> +
> + /*
> + * Type 1 adaptors are limited to 165MHz
>
> + * Type 2 adaptors can tells us their limit
"can tells"
> + */
> + ret = drm_dp_dual_mode_read(adapter,
> DP_DUAL_MODE_MAX_TMDS_CLOCK,
> + &max_tmds_clock,
> sizeof(max_tmds_clock));
> + if (ret)
Maybe also "if (ret || max_tmds_clock == 0 || max_tmds_clock == 0xFF)"?
> + return 165000;
> +
> + return max_tmds_clock * 5000 / 2;
> +}
> +EXPORT_SYMBOL(drm_dp_dual_mode_max_tmds_clock);
> +
> +/**
> + * drm_dp_dual_mode_get_tmds_output - Get the state of the TMDS
> output buffers in the DP dual mode adaptor
> + * adapter: I2C adapter for the DDC bus
> + * enabled: current state of the TMDS output buffers
> + *
> + * Get the state of the TMDS output buffers in the adaptor.
> + * DP_DUAL_MODE_TMDS_OEN register is mandatory for type 2 adaptors,
> + * optionals for type 1 adaptors. Hoever, as some type 1 adaptors
> are
> + * broken (see comments in drm_dp_dual_mode_detect() for the
> details)
> + * one probably shouldn't use this with type 1 adaptors at all.
> + *
> + * Returns:
> + * 0 on success, negative error code on failure
> + */
> +int drm_dp_dual_mode_get_tmds_output(struct i2c_adapter *adapter,
> bool *enabled)
> +{
> + uint8_t tmds_oen;
> + ssize_t ret;
> +
> + ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
> + &tmds_oen, sizeof(tmds_oen));
> + if (ret)
> + return ret;
> +
> + *enabled = !(tmds_oen & DP_DUAL_MODE_TMDS_DISABLE);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_dp_dual_mode_get_tmds_output);
> +
> +/**
> + * drm_dp_dual_mode_set_tmds_output - Enable/disable TMDS output
> buffers in the DP dual mode adaptor
> + * adapter: I2C adapter for the DDC bus
> + * enable: enable (as opposed to disable) the TMDS output buffers
> + *
> + * Set the state of the TMDS output buffers in the adaptor.
> + * DP_DUAL_MODE_TMDS_OEN register is mandatory for type 2 adaptors,
> + * optionals for type 1 adaptors. Hoever, as some type 1 adaptors
> are
> + * broken (see comments in drm_dp_dual_mode_detect() for the
> details)
> + * one probably shouldn't use this with type 1 adaptors at all.
> + *
> + * Returns:
> + * 0 on success, negative error code on failure
> + */
> +int drm_dp_dual_mode_set_tmds_output(struct i2c_adapter *adapter,
> bool enable)
> +{
> + uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE;
> + ssize_t ret;
> +
> + ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
> + &tmds_oen, sizeof(tmds_oen));
> + if (ret)
> + return ret;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output);
> +
> +/**
> + * drm_dp_get_dual_mode_type_name - Get the name of the DP dual mode
> adaptor type as a string
> + * type: DP dual mode adaptor type
> + *
> + * Returns:
> + * String representation of the DP dual mode adaptor type
> + */
> +const char *drm_dp_get_dual_mode_type_name(enum
> drm_dp_dual_mode_type type)
> +{
> + switch (type) {
> + case DRM_DP_DUAL_MODE_NONE:
> + return "none";
> + case DRM_DP_DUAL_MODE_TYPE1_DVI:
> + return "type 1 DVI";
> + case DRM_DP_DUAL_MODE_TYPE1_HDMI:
> + return "type 1 HDMI";
> + case DRM_DP_DUAL_MODE_TYPE2_DVI:
> + return "type 2 DVI";
> + case DRM_DP_DUAL_MODE_TYPE2_HDMI:
> + return "type 2 HDMI";
> + default:
> + return "unknown";
Please at least WARN_ON(1)?
And, if you implement my suggestion of adding an actual unknown value
to the enum, don't forget to change the default case to return
something that's not "unknown".
Most of the things I wrote above are just ideas, not requirements, and
having this patch as-is looks better than not having it, so if you at
least fix the spelling errors:
Reviewed-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
> + };
> +
> +}
> +EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
> diff --git a/include/drm/drm_dp_dual_mode_helper.h
> b/include/drm/drm_dp_dual_mode_helper.h
> new file mode 100644
> index 000000000000..a2f6b4587f5f
> --- /dev/null
> +++ b/include/drm/drm_dp_dual_mode_helper.h
> @@ -0,0 +1,80 @@
> +/*
> + * Copyright © 2016 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person
> obtaining a
> + * copy of this software and associated documentation files (the
> "Software"),
> + * to deal in the Software without restriction, including without
> limitation
> + * the rights to use, copy, modify, merge, publish, distribute,
> sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom
> the
> + * Software is furnished to do so, subject to the following
> conditions:
> + *
> + * The above copyright notice and this permission notice shall be
> included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
> EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
> EVENT SHALL
> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM,
> DAMAGES OR
> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
> OTHERWISE,
> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
> USE OR
> + * OTHER DEALINGS IN THE SOFTWARE.
> + */
> +
> +#ifndef DRM_DP_DUAL_MODE_HELPER_H
> +#define DRM_DP_DUAL_MODE_HELPER_H
> +
> +#include <linux/types.h>
> +
> +/*
> + * Optional for type 1 DVI adaptors
> + * Mandatory for type 1 HDMI and type 2 adators
> + */
> +#define DP_DUAL_MODE_HDMI_ID 0x00 /* 00-0f */
> +#define DP_DUAL_MODE_HDMI_ID_LEN 16
> +/*
> + * Optional for type 1 adaptors
> + * Mandatory for type 2 adators
> + */
> +#define DP_DUAL_MODE_ADAPTOR_ID 0x10
> +#define DP_DUAL_MODE_REV_MASK 0x07
> +#define DP_DUAL_MODE_REV_TYPE2 0x00
> +#define DP_DUAL_MODE_TYPE_MASK 0xf0
> +#define DP_DUAL_MODE_TYPE_TYPE2 0xa0
> +#define DP_DUAL_MODE_IEEE_OUI 0x11 /* 11-13*/
> +#define DP_DUAL_IEEE_OUI_LEN 3
> +#define DP_DUAL_DEVICE_ID 0x14 /* 14-19 */
> +#define DP_DUAL_DEVICE_ID_LEN 6
> +#define DP_DUAL_MODE_HARDWARE_REV 0x1a
> +#define DP_DUAL_MODE_FIRMWARE_MAJOR_REV 0x1b
> +#define DP_DUAL_MODE_FIRMWARE_MINOR_REV 0x1c
> +#define DP_DUAL_MODE_MAX_TMDS_CLOCK 0x1d
> +#define DP_DUAL_MODE_I2C_SPEED_CAP 0x1e
> +#define DP_DUAL_MODE_TMDS_OEN 0x20
> +#define DP_DUAL_MODE_TMDS_DISABLE 0x01
> +#define DP_DUAL_MODE_HDMI_PIN_CTRL 0x21
> +#define DP_DUAL_MODE_CEC_ENABLE 0x01
> +#define DP_DUAL_MODE_I2C_SPEED_CTRL 0x22
> +#define DP_DUAL_MODE_LAST_RESERVED 0xff
> +
> +struct i2c_adapter;
> +
> +ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
> + u8 offset, void *buffer, size_t size);
> +ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
> + u8 offset, const void *buffer, size_t
> size);
> +
> +enum drm_dp_dual_mode_type {
> + DRM_DP_DUAL_MODE_NONE,
> + DRM_DP_DUAL_MODE_TYPE1_DVI,
> + DRM_DP_DUAL_MODE_TYPE1_HDMI,
> + DRM_DP_DUAL_MODE_TYPE2_DVI,
> + DRM_DP_DUAL_MODE_TYPE2_HDMI,
> +};
> +
> +enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct
> i2c_adapter *adapter);
> +int drm_dp_dual_mode_max_tmds_clock(struct i2c_adapter *adapter);
> +int drm_dp_dual_mode_get_tmds_output(struct i2c_adapter *adapter,
> bool *enabled);
> +int drm_dp_dual_mode_set_tmds_output(struct i2c_adapter *adapter,
> bool enable);
> +const char *drm_dp_get_dual_mode_type_name(enum
> drm_dp_dual_mode_type type);
> +
> +#endif
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